The Unicode Consortium sets the international standards for
characters — like emoji — across different software platforms,
like iOS and Android. When Unicode introduces new emoji characters for Unicode 8.0,
which gets released mid-2015, they can be integrated into your
emoji keyboard.

"These are candidates—not yet finalized—so some may not appear in
the release," Unicode Consortium's post warns. "There are many
possible emoji that could be added, but releases need to be
restricted to a manageable number."

These emoji would be compatible with other messaging and email
systems: